I am not surprised by this. The earnings must be about $25k per person, not per family. If it's per family then it must be so after adjusting for several other factors (which I am not aware of).

Only handful of Nepalese are making good money now especially the ones who are in IT sector and second to that the ones in academia sector (who have minimum of graduate school education).
While lots of Nepali students and family who come here belong to a middle class (upper, middle, lower) back in Nepal, they slid down to lower socioeconomic class as soon as they enter the land of USA. But, they do have a good prospect of skills (only mid level though, not too high) to pull and float about the lower middle class section of the overall USA society.

Just in about a generation I expect to see two classes of these Nepalese immigrants - the ones (but only a handful) who succeeded economically to middle middle class of American society. This is mostly made possible due to the job opportunities in the IT sector and few from research academic and financial disciplines. While other will just float around the lower middle class or slide even lower as the new generation takes over.

Here is a good article I would like to share: https://www.financialsamurai.com/income-by-race-why-is-asian-income-so-high/

Most of the people tend to have a very limited knowledge of the capacity of the person from Nepalese socio economic background. The national and global average of the skill of people from Nepal is very low to mid, but I think new generation will do better but still only a few handful will show the talent.